From owner-freebsd-hackers@freebsd.org Wed Mar 30 11:30:42 2016 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 0A06BAE3792 for ; Wed, 30 Mar 2016 11:30:42 +0000 (UTC) (envelope-from s3erios@gmail.com) Received: from mail-lf0-x22d.google.com (mail-lf0-x22d.google.com [IPv6:2a00:1450:4010:c07::22d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 8540D1383 for ; Wed, 30 Mar 2016 11:30:41 +0000 (UTC) (envelope-from s3erios@gmail.com) Received: by mail-lf0-x22d.google.com with SMTP id k79so33571397lfb.2 for ; Wed, 30 Mar 2016 04:30:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=to:subject:references:date:mime-version:content-transfer-encoding :from:message-id:in-reply-to:user-agent; bh=iXKAuCVaUQuyBZH3LVzq46VYj7s0zS/xYiaZ/7dQESk=; b=f7L78B4SfNhDSOZpMhBquvbfjwAwHmmOQfs12PfqreRHxUK69+CQp2L5zuzDydxFmy W0n8xc9CCngFbgiVGXpS2d0xqJAYsdKdamjI9Twn6L+5BHfVM45NhAsgNqd4UOTXebH7 GxkOWwmj8BEv8KoSNJVhd7I6bXvC2H9Cs+a5WAYaE5DekQyGkUkfxI+MNFs+hna/+qeS 8pL7PQPjSTVyMWPq9wHHVg7hXG3FT559CMyB0LH9pnQeLNcFvxvwlf9tR6dTteyqcObd otBzUrR6P2MazY3sRcdxBTWJHWIVZL8qY5ednmH156bwOj5YMZfMyL+bE2j6B6cOVb60 pTVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:subject:references:date:mime-version :content-transfer-encoding:from:message-id:in-reply-to:user-agent; bh=iXKAuCVaUQuyBZH3LVzq46VYj7s0zS/xYiaZ/7dQESk=; b=O4WZt7J7KbUzJwr5WDbZfElV1/awq6IroKGTxr0XXcrtlpMGQBZsjOkmKfHeysEc0T WWjYvmBqCDPbXgQCwlt9gP1llSpWmIAEysOcNiAd+Z+ow7vrsc/D5SbQda5+MbQbS5A7 QpRtf5g4gZZdWOvgfUYI/8z6ltWza26LAnYlsoOYiZ5OkihFR9uW3aOzs/hkIl8owiv8 CR1P/zjJCxTpR50uc5uNEwRBLAuu9p2SvmhBFxE+yCd3K537HxihvL2aUCG1mVDSEjMw gcSu1VucYv85THT+rPSBpjwJnJZueH4MM2Cmoxo2fo3bXCATGKPBJft0sAt50kSjEjP6 HTJg== X-Gm-Message-State: AD7BkJIAqRTR5wabFPt7oNg/hEXVtSxjkkfMbmpkGgck7/OXkV93+Wob4/czyTGOj1OpyQ== X-Received: by 10.25.15.75 with SMTP id e72mr3580989lfi.148.1459337439870; Wed, 30 Mar 2016 04:30:39 -0700 (PDT) Received: from localhost ([77.91.171.160]) by smtp.gmail.com with ESMTPSA id i2sm490034lfd.43.2016.03.30.04.30.38 (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 30 Mar 2016 04:30:39 -0700 (PDT) Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes To: freebsd-hackers@freebsd.org, "Aleksander Alekseev" Subject: Re: I need a little help in fixing `exclusive sleep mutex urtwn0_com_lock` in CURRENT References: <20160330123048.3361a9e4@fujitsu> Date: Wed, 30 Mar 2016 14:30:41 +0300 MIME-Version: 1.0 Content-Transfer-Encoding: Quoted-Printable From: "Andriy Voskoboinyk" Message-ID: In-Reply-To: <20160330123048.3361a9e4@fujitsu> User-Agent: Opera Mail/12.16 (FreeBSD) X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Mar 2016 11:30:42 -0000 Wed, 30 Mar 2016 12:30:48 +0300 =D0=B1=D1=83=D0=BB=D0=BE =D0=BD=D0=B0=D0= =BF=D0=B8=D1=81=D0=B0=D0=BD=D0=BE Aleksander Alekseev = : > and then pull Wi-Fi adapter out of USB Here (it's not the only driver which does detach incorrectly). > Hello > > Today I found a way to crash CURRENT kernel. I'm a full-time *nix C > developer but I never did kernel development before. I read "FreeBSD > Device Drivers" and "FreeBSD Developer's Handbook" recently. Also I > learned how to use DDB and KGDB. Discovered problem doesn't seem to be= > too complicated and I hope you could guide me a little bit through > fixing it. > > I'm using TP-LINK TL-WN725N USB Wi-Fi adapter. When I do: > > sudo ifconfig wlan0 down > sudo ifconfig wlan0 up > > ... and then pull Wi-Fi adapter out of USB kernel crashes like this: > > http://pastebin.com/raw/LkuE6Y7s > > It reproduces in 100% of cases. > > Here is a code that causes a problem (ieee80211_scan_sw.c:765): > > ``` > static void > scan_end(struct ieee80211_scan_state *ss, int scandone) > { > struct scan_state *ss_priv =3D SCAN_PRIVATE(ss); > struct ieee80211vap *vap =3D ss->ss_vap; > struct ieee80211com *ic =3D ss->ss_ic; > > IEEE80211_LOCK_ASSERT(ic); > > IEEE80211_DPRINTF(vap, IEEE80211_MSG_SCAN, "%s: out\n", > __func__); > > if (ss_priv->ss_iflags & ISCAN_ABORT) { > scan_done(ss, scandone); > return; > } > > IEEE80211_UNLOCK(ic); > ic->ic_scan_end(ic); /* notify driver */ > IEEE80211_LOCK(ic); /* <--- HERE */ > ``` > > So as I understand some code acquired a mutex and didn't release it. > And naturally it has something to do with USB. Now how can I figure ou= t > what code acquired this lock? Best approach I can think of currently i= s > to find all places where this lock is accessed and add a debug logging= . > But perhaps there is a better way?